I have a custom button which open new event page and after I save it is going back to home page or opportunity detail page when the retURL is passed. How can I make it to go to the new event detail page?

I am working on a requirement where the button calls the visualforce page , I want this button to call the page only when it verifies if the ownerId = Current user ID

if( "$User != OwnerID") { 
alert( "Please own the record to edit it"); 
} 
else { 
window.top.location.href=https://xxxxxxxxxxxxxxx2crm.xxxxdev.shnpoc.net/066210000004GnC
}

I am not sure of the syntax here and what should I give in the URL the page address or some other way?

Upto how many levels can we apply the cross object formula field? Please post relevent material if available.